I. Field of the Invention
This invention relates generally to electronic data processing equipment and specifically to an interface for interconnecting a terminal comprising a printer and a keyboard with a central data processing unit.
II. Description of the Prior Art
Large scale electronic data processing equipment is generally housed in specially prepared buildings and operated by extensive support personnel. Thus, it has become common practice in the data processing industry to provide for the exchange of data information between a number of remotely located data terminals and a central data processing unit. This exchange of data information takes place through long transmission or communication lines, such as telephone lines. In order to provide compatibility throughout many product lines and among many manufacturers, standardized data codes and formates have been established. One of the most widespread codes is ASCII (American Standard Coding Scheme). The data is transmitted serially through the lines as a fixed length time sequence of electronic pulses.
Coded information data can be more rapidly and efficiently transmitted in a parallel data format. For example, rather than transmitting a fixed length time sequence of pulses for each data character, the character may be transmitted simultaneously over a plurality of conductors, each of which corresponds to a time segment of the fixed length time sequence of pulses in a serial data format. An information character coded in ASCII data format and transmitted serially requires, in addition to timing pulses, a signal length seven pulses long. The same data character may be transmitted in a parallel format through seven conductors simultaneously.
Many recently designed pieces of electronic data processing equipment, such as printers and keyboards, have been designed to handle data more efficiently in a parallel data format. Such pieces of electronic data processing equipment are generally not compatible with electronic data processing equipment designed to transmit and receive information data serially. Because of this limitation, the number of applications in which this recently designed equipment may be utilized is greatly restricted.